1. Technical Field
The present invention relates generally to high-performance, fault-tolerant content delivery and, in particular, to systems and methods for balancing loads from mirrored data centers within a global computer network.
2. Description of the Related Art
It is known to store Web-based content in mirrored data centers and to load-balance such content requests to data centers based on network traffic conditions. Existing global load balancing products use several different approaches for building a map of Internet traffic conditions. One approach uses border gateway protocol (BGP) data. BGP-based routing, however, can be sub-optimal because the BGP data can be very coarse. Other approaches attempt to compute an optimal mapping in real-time and then cache the mapping information. This technique can lead to poor turnaround time during an initial “hit” and potentially stale mappings on successive requests. In addition, the quality of the measurement to the endpoint tends to be noisy. Because of the deficiencies of these mapping techniques, the resulting load balancing is less than effective.
Current load balancing devices are typically incapable of computing an optimal map for an entire computer network such as the entire Internet. Presently, the Internet has hundreds of millions of hosts and routers. Estimating the connectivity time of the entire Internet to a set of mirrored data centers, such as by evaluating the network path between a server and each and every host or router, would be incredibly time-consuming and would consume far too much bandwidth. Such techniques, of course, are impractical when real-time routing decisions are required.
Further, such measurements tend to be noisy and inaccurate, and they can annoy system administrators whose firewalls are contacted. Local name servers behind firewalls would not be reached and slow connectivity over the “last mile” (e.g., due to dial-up connections and the like) tend to confuse the connectivity picture. Consequently, there remains no efficient technique in the prior art for generating an optimal network connectivity map that can be used for providing intelligent traffic redirection in conjunction with load balancing across mirrored data centers located around the globe.